JPS6392055A - Image reading apparatus - Google Patents

Abstract

PURPOSE:To secure sufficient image reading performance, by inputting illumina tion light through a part, which is closer to a switch part viewed from a posi tion to be read, directing the component of the light reflected from the position to be read on an original toward the direction that is distant from the switch part, and reducing the amount of light reaching the switch part. CONSTITUTION:A light source 230 is arranged on the side of a switch part 213 viewed from a position to be lighted on the surface of an original. There fore, the position to be lighted on the surface of the original P is distant from the switch part 213. The component of the light, which undergoes mirror reflec tion at the interface of a protective layer 229 of the light and the component of the light, which undergoes mirror reflection at the surface of the original P, are directed toward the direction distant from the switch part 213. Therefore almost no luminous flux or a very small amount of luminous flux propagates in the protective layer 229 and reaches the switch part 213. Thus, a special member for blocking the input of the light into the switching part is not required. The incident light into the switch part 213 is decreased with a simple constitution, and stability in image reading can be secured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an image reading device, which includes, for example, a -dimensional line sensor, and which reads an image of a document in close contact with the -dimensional line sensor. The present invention relates to an image reading device suitable for application to facsimile machines, image readers, etc., which reads image information while relatively moving the image information.

[Prior Art] Conventionally, this type of image reading device called a close-contact type uses a rod lens array to read an image on a document surface by projecting it onto an optical sensor having a photoelectric conversion element or a group thereof. Many things have been created that do this.

In contrast, recently, with the aim of reducing costs and further downsizing, images have been read by using an optical sensor coated with a thin transparent protective layer and directly contacting the document, without using a rod lens array. There is active development of new products.

In addition, it is known that the switching element for driving the optical sensor and switching its output is composed of a thin film transistor (TPT), and this is formed simultaneously on the same substrate as the optical sensor in the same manufacturing process. It is being

FIG. 5 shows an example of a conventional image reading device of this type. Here, 1 is an optical sensor section, and 2 is a capacitor that accumulates the output of the optical sensor section 1. 3 is a switch section for transferring the charge accumulated in the capacitor section 2 for signal processing, and is a TPT having almost the same laminated structure as the optical sensor section 1.
It consists of Each of these parts 1 to 3 is formed on a light shielding layer 5 provided on a transparent substrate 4, and the window portion (portion where the light shielding layer 5 is not formed) is located from the light source 8 disposed on the back side of the substrate 4.
The light that enters through the light source 9 and is reflected by the surface of the document P is received by the optical sensor section 1 .

On the other hand, the distance between the original P and the sensor unit 1 is usually 0.1
A reading resolution of 4 to 8 wood/mo+ can be obtained for approximately 4 mm, but in order to ensure such resolution, the above-mentioned spacing must be strictly controlled.

The spacing is controlled by coating the upper surface of the sensor part l with a transparent protective layer 20.

In such a configuration, the light beam enters the optical sensor section 1, and then reaches the sensor section 1 and the surface of the document P.

Since it is reflected and diffused at the interface of the protective layer 20 and the like, a part of this luminous flux may reach the switch section 3.

However, since the switch section 3 has substantially the same configuration as the optical sensor section 1, its characteristics change when light is incident, which has a serious adverse effect on image reading performance.

[Problems to be Solved by the Invention] In order to prevent such light from entering the switch section 3, as shown in FIG.
A light shielding layer 3B made of metal or the like may be provided through the
As shown in the figure, it is conceivable to provide a light absorption layer 208 on the protective layer 20 in order to eliminate the reflection of light toward the switch section 3.

However, using such a configuration unnecessarily complicates the manufacturing process of the image reading device and increases the price. It's hard to say that I made the most of it.

The present invention focuses on the incident direction of light, which has not been considered in the past, and determines the direction appropriately, thereby making it possible to eliminate or significantly reduce the incidence of light into the switch section without strict light shielding. , the purpose is to solve the above problems.

[Means for Solving the Problems] In order to achieve the above object, the present invention includes an optical sensor provided on a substrate, and an optical sensor provided on the substrate with the same configuration as the optical sensor. In an image reading device that includes a switch section that performs switching, illuminates a position to be read on a document surface with illumination light from the back side of a substrate through a window section, and receives the reflected light on an optical sensor, the illumination light is It is characterized in that the light is incident from the side closer to the switch section when viewed from the position to be read.

[Operations] That is, according to the present invention, the component of the light reflected at the reading position of the document is directed in a direction far from the switch section, so that the amount of light reaching the switch section is significantly reduced.

[Example] Hereinafter, the present invention will be described in detail with reference to the drawings.

FIGS. 1(^), (B) and (C) are plane views showing an example of an image reading device in which an optical sensor section, a charge storage section (capacitor section), a switch section, etc. are integrally formed, respectively. , its BB sectional view and CC line sectional view are shown.

In this example, a plurality of optical sensor sections 208 and the like corresponding to one bit of image reading are arranged in a line on the substrate.
This is a one-dimensional line sensor. For example, the width direction of the original P (direction perpendicular to the moving direction of the original fA P)
8 wood/mm over 216mm equivalent to A4 size
If the resolution is to be provided, 1728 optical sensor sections 208 can be arranged.

In addition, in this example, the optical sensor section, the capacitor section that accumulates the output of the optical sensor section, the switch section that transfers the accumulated charge and uses it for signal processing, and the necessary wiring pattern etc. It is formed on the substrate during the manufacturing process.

In FIGS. 1(A) to (C), 201 is a transparent substrate;
210 is a matrix wiring section, 208 is a light sensor section, 21
2 is a charge storage unit; 213 is a switch unit including a transfer switch 213a and a discharge switch 213b for resetting the charge in the charge storage unit 212; 214 is a wiring that connects the signal output of the transfer switch to an appropriate signal processing unit; 223
is a load capacitor for accumulating and reading out the charge transferred by the transfer switch 213a.

An a-5i:If film is used as the semiconductor layer 14, and a silicon nitride film (S) is used as the insulating layer 203.
iNH) is used.

In addition, in FIG. 1 (8), in order to avoid complexity, only the upper and lower two layers of electrode wiring are shown, and the photoconductive semiconductor layer 14 is
, the insulating layer 203 and the protective layer 229 are not shown.

Furthermore, the photoconductive semiconductor layer 14 and the insulating layer 203 include a photosensor section 208, a charge storage section 212) and a transfer switch 213.
In addition to being formed on the discharge switch 213b and the discharge switch 213b, it is also formed between the upper layer electrode wiring and the substrate. Furthermore, at the interface between the upper type 8i wiring and the photoconductive semiconductor layer, n3
A doped a-5i:H layer 205 is formed to form an ohmic contact.

In addition, in the wiring pattern of the line sensor of this embodiment, all signal paths output from each sensor section are wired so as not to intersect with other wiring, and crosstalk between each No. 8 component and the gate electrode Prevents induced noise from wiring.

In the optical sensor section 208, 218 and 217 are upper layer electrode wirings. Switch section 2 when viewed from the image reading position
From the light source 230 located on the side closer to the entrance window 219
The light incident on the document surface and reflected on the document surface is a-5i:
By changing the conductivity of the photoconductive semiconductor layer 14, the current flowing between the upper layer electrode wirings 216 and 217 facing each other in a comb shape is changed. Note that 202 is a light shielding layer made of metal or the like.

The charge storage section 212 is formed on the lower electrode wiring 214, the insulating layer 203 formed on the lower electrode wiring 214, the photoconductive semiconductor 14, and the photoconductive semiconductor layer 14, and serves as an optical sensor. The upper layer electrode wirings 2 and 7 are connected to each other. The structure of this charge storage section 212 is the so-called old S (Metal-1nsulater-5emi) structure.
conductor): Same structure as the 7 conductor. Although either positive or negative bias conditions can be used, stable capacitance and frequency characteristics can be obtained by always biasing the lower electrode wiring 214 negatively.

In the figure, (C) shows a switch section 213 having a TFT structure including a transfer switch 213a and a discharge switch 213b. and an insulating layer 203 forming a gate insulating layer,
It is composed of a photoconductive semiconductor layer 14, an upper layer electrode wiring 225 serving as a source electric fence, an upper layer electrode wiring 217 serving as a train electrode, and the like. The gate insulating layer and photoconductive semiconductor layer of the discharge switch 213b are the same layer as the insulating layer 203 and the photoconductive semiconductor layer 14, the source electrode is the upper layer electrode wiring 217, and the gate electrode is the lower layer electrode wiring 227 (of the switch 213b). (also functions as a light shielding layer), and the drain electrode is the upper electrode wiring 226. Moreover, 234 is a lower layer wiring connected to the gate electrode of the transfer switch 213a.

As mentioned above, at the interface between the upper electrode wirings 217, 225, and 226 and the photoconductive semiconductor layer 14, a-5
A t:H n+ layer 205 is interposed to form an ohmic contact.

As described above, the line sensor according to this example includes an optical sensor section,
Since each component of the charge storage section, transfer switch, discharge switch, and matrix wiring section all has a laminated structure of a photoconductive semiconductor layer, an insulating layer, etc., each component can be formed simultaneously by the same process.

FIG. 2 schematically shows the image reading device shown in the first drawing, and the effects of the embodiment shown in the first drawing will be explained using this figure.

In the conventional device (Fig. 5), a part of the light beam reflected by the original fAP plane is repeatedly reflected by the protective layer interface, the wiring pattern near the photoelectric conversion element, etc., and reaches the switch section. In the example, since the light source 230 is arranged on the switch section 213 side when viewed from the illuminated position on the document surface, the illuminated position on the document P side is farther from the switch section 213 than in the configuration shown in FIG.

In addition, the component that is specularly reflected at the interface of the light protective layer 229 and the component that is specularly reflected at the surface of the original fAP are
Since the light beam is directed in a direction further away from the light beam, there is almost no light flux that propagates within the protective layer 229 and reaches the switch section 213, or at least it is significantly smaller than in the conventional example.

In other words, according to this example, the light incident on the switch section 213 can be reduced with a simple configuration and the stability of image reading can be ensured without providing a special member to prevent light from entering the switch section 213. .

3 and 4 are respectively a perspective view showing another embodiment of the present invention and an explanatory view schematically showing a cross section taken along the line AA', and FIGS. Components similar to those in the embodiment shown in FIG. 2 and FIG. 2 are designated by the same reference numerals. In this example, the window for introducing the illumination light of the original P is the optical sensor section 208 and the switch section 21.
It is provided between 3 and 3.

In the image reading device according to this embodiment, since specular reflection light from the interface of the protective layer 229 and the surface of the original 2 directly enters the optical sensor unit 208, the resolution tends to deteriorate somewhat; Even when the layer 229 is not in close contact with the surface and is being transported slightly floating as shown in the figure, or when the thickness of the protective layer 229 is not uniform, the sensor may Since the amount of light incident on the section 208 does not change much, there is an advantage that stable image reading can be performed.

[Effects of the Invention] As explained above, according to the present invention, the incident direction of the document illumination light beam is made to enter from the side closer to the switch section with respect to the position to be read on the document surface. The amount of light incident on the switch section can be reduced with a simple configuration.

That is, according to the present invention, it is possible to obtain the excellent effect that sufficient image reading performance can be ensured with respect to the switch portion without providing a special light shielding means as in the prior art.

[Brief explanation of the drawing]

Figures 1 (A), (B) and (C) are, respectively,
FIG. 2 is a plan view showing an embodiment of an image reading device in which an optical sensor section, a charge storage section, a switch section, etc. are integrally formed, a sectional view taken along the line B-B, and a sectional view taken along the line C-C. is an explanatory diagram schematically showing a cross section of the embodiment shown in the first figure in order to explain the function and effect thereof, FIG. 3 is a perspective view showing another embodiment of the present invention, and FIG. FIG. 5 is an explanatory diagram schematically showing an example of a conventional image reading device; FIG. 6 and FIG. 2 of an image reading device in which a light shielding member is provided for a switch section in the conventional example of
It is an explanatory diagram showing an example. 1.208... Optical sensor section, 2.212... Capacitor section, 3.213... Switch section, 4.201... Transparent substrate, 5.20'2, 214, 224, 227...・Light blocking layer,
8.230... Light source, 9.219... Entrance window, 14... Semiconductor layer, 20.229... Protective layer, 216.217... Electrode (wiring), P... Document, S...light. Figure 1 Figure 5 Figure 6

Claims (1)

[Claims] 1) A device comprising: a substrate, an optical sensor provided on the substrate, and a switch section provided on the substrate with the same configuration as the optical sensor and switches the output of the optical sensor. , an image reading device in which illumination light is irradiated from the back side of the substrate through a window to a position to be read on a document surface, and the reflected light is received by the optical sensor, wherein the illumination light is transmitted from the position to be read. An image reading device characterized in that light is incident from a side closer to the switch section when viewed from above. 2) The image reading device according to claim 1, wherein the substrate has a light transmitting property, and the optical sensor and the switch section are arranged on the substrate with a light shielding layer interposed therebetween. image reading device. 3) The image reading device according to claim 1 or 2, wherein a light source for irradiating the illumination light is arranged near the switch section on the back side of the substrate.